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Cattech

Hyd schematic

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Cattech    0

Does anybody have a PDF copy of the full tractor hyd schematic, possibly some of the service manual for a JD 4320. It has a new belly pump and a new front pump. It has the common issue of cranking the steering wheel back and forth when trying to start it and it doesn't generate the hyd flow it should at the remotes - it doesn't have enough to keep the planter blower running at low idle - the 3010 has no problem. We've been nursing it along for a couple of seasons, but it's time to figure it out.

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GT&T    0

Cattech

     I have been following your comments in the past, and know, "you know your stuff".  I only add this in case you are not aware of it.   The John Deeres use a long tubular screen that runs crossways in the base of the rear center case.  This screen may be 1" to 1 1/4" in Diam. and may be 1/8"  mesh,  it is a course mesh.   It is accessed by a large plug on each end that may have a fitting or elbow, depending on the application.   One end plug may have a 1/2" square socket that a 1/2" ratchet will fit.   I have found many times that when the oil lubricated & oil cooled brakes begin to fail the residue from the brake failure will plug the screen.  Since the John Deeres use a closed hydraulic system, the system will build pressure but will not perform up to the flow needs, when you try to flow oil, to a high flow hydraulic motor.

     If you have a hard time removing this screen, it may because the screen is coated with trash.   You may have already verified that this screen is cleaned, if you have then I would pull it again, just to verify that it has not been recontaminated.

     I'm sorry that I don't have a schematic for your tractor.

GT&T

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pete23    0

I don't have a schematic for that tractor either.  I do have a few manuals they were throwing away at the dealer when I worked there but they are for newer like 50 series.  

What I found interesting about your comments  was the steering wheel.  One of the first things I learned at Deere dealer was, don't put your hand through the spokes of a steering wheel when starting the engine  on those older tractors.  Most didn't move or very little but some of them were violent.  I used to put my hand between the steering wheel spokes on some model IH tractors to push the starter button.

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What GT&T says is entirely possible, what we used to do on those was to put a couple of cow magnets inside the screen when we had one out.

I have seen these screens totally collapsed from the trash they have stopped.

#39

 

 

Also, the pickup tube to the lube pump that is driven by the hex-shaft has been known to crack just above where it pushes into the transmission case, and have you changed the hoses to the other SCV to see if either the SCV is faulty, or the linkage is worn enough to keep the internal valves from opening.

Since you say that the lube pump was replaced/rebuilt, the long hex shaft should be good, when they fail, they round off the hex at the spot where it drives the lube pump gear, and everything quits.

RWP2546________UN01JAN94.gif

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RKO    0

Agree you should check screen first. If it's ok then check to make sure you don't have an internal leak in the system. The oil is pumped by the transmission pump to the front pump. There is a line inside The transmission that can break.   Next I would check the three point cylinder for leaks if the rings are bad on the cylinder the pump can not keep up with the leak. There is also a check valve on the cylinder that can go bad. Also the o ring between the rock shaft housing and transmission housing could be bad. Have you tried another valve on this tractor to run motor. The valve could be bad. I've seen them break inside or the shaft for the oil flow rate will break and you think you have full flow 

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1466fan    0

Got a 2940 that acted up for a while. Would lose all hydraulics if it idled very long. The Steel line that comes out of the Pump had kind of bound or cocked I guess when I had slid the tractor back together. It was letting Oil by pass at the end of the tube. Finally pushed the tube out one day this winter when it was real cold. On the 29 I could drain the hydraulic Oil and pull a plate off right below where this line is. Pulled it off this time to double check the line. Fixed all my hydraulic issues. It works great now.

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dale560    0

First things first here on the 4320. What everyone else said is spot on. But we will start here. Was your main hydraulic pump new or rebuilt? The 4320 does not use the hex shaft that is 30 series and later. The oil is pumped up by trans pump when clutch is released to main pump. A quick way to check trans pump is pull filter and turn engine over it should flow about 1 gal a minute on starter turning tractor. The oil is pumped up the side of tractor to main pump. Then main pump back to priority valve in steering column by the shift handle. Then hydraulic functions by a pipe along floor board to rock shaft housing. If you have a hydraulic hose any place on tractor instead of pipes get rid of them and replace with factory pipe. The screen in trans will plug but that is easy fix. There is a little screen in main pump also. The steering and brake have priority at the valve over hydraulics but very seldom trouble with priority valve. If your main hyd pump was rebuilt your exhaust or intake.  valves can be bad affecting flow and there are outlet and stroke control valves that need to be adjusted on pump.  My 2 cents here check screen in trans then check main pipe up the left side of tractor. This needs to be the original pipe.the steering wheel to start is a common thing on JD especially if your starter is getting weak. If everything is good up to main pump the only thing that it can be is the pump itself. I have only seen problems with the priority valve once and that was my own doing. It is a fairly easy system to diagnose if you find a manual even a I T manual covers it okay. There is a gasket on the manifold  for the trans pump and an  o ring on those pipes but they should be okay.

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dale560    0

In arts picture of the trans pump oil is sucked up the right side and pumped out the left side make sure your orings on left side pipe are good the check valve at the bottom just holds oil when pump is stopped , engine off or clutch in. The gasket and pipe onto pinion are for trans lube . Make sure this pipe is in place or big problems will occur. Good luck with it used to fix about one JD pump every other week.

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Cattech    0

I'm going to look at the screen and replace the filter in the morning. It wouldn't surprise me in the least to find that screen plugged solid. Dad doesn't exactly believe in maintenance, unless they cleaned that screen at the shop when he took it in for the pumps, it's never been out of the tractor. I don't even recall the trans oil getting changed in the last 25 yrs.

It would make a lot of sense that the screen got plugged up..... The tractor gave zero issues up until dad bought that planter..... In the previous 30 yrs, the hyds only run cylinders, and the thing only gets 50 hrs a yr of use, so there probably was 25 plus yrs of brake lining, wear material, dust and dirt silted on the bottom of the cases.... and then we started running a hyd motor with a return directly into the diff housing.... which most likely stirred everything up and rinsed it into the screen.

After the first planting season the belly pump shelled out when dad was applying anhydrous. He took it in to Scharber's for the repair. It worked fine for a while, but then the front pump quit... back to the dealer where that got replaced. It still didn't seem right, but we used it anyway. 

I have been thinking it had something to do with the priority valve and the steering since turning the wheel would make it turn over easier. I also have read a few things about low pressure losses starving the high pressure pump.... such as the PTO control valve, and there was mention of a check valve in the forward flowing supply line. I have suspected that pickup tube and hope thats not it. I admit I didn't even know about the pick up screen, I've never been inside a 10 or 20 series Deere behind the clutch housing beyond youtube videos. 

Hopefully it's as simple as cleaning the screen, I won't tell ol dad what I did to fix it and can keep my #1 son status ;) I appreciate everyone's input and will keep you posted, thanks.

SW

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dale560    0
4 hours ago, Cattech said:

I'm going to look at the screen and replace the filter in the morning. It wouldn't surprise me in the least to find that screen plugged solid. Dad doesn't exactly believe in maintenance, unless they cleaned that screen at the shop when he took it in for the pumps, it's never been out of the tractor. I don't even recall the trans oil getting changed in the last 25 yrs.

It would make a lot of sense that the screen got plugged up..... The tractor gave zero issues up until dad bought that planter..... In the previous 30 yrs, the hyds only run cylinders, and the thing only gets 50 hrs a yr of use, so there probably was 25 plus yrs of brake lining, wear material, dust and dirt silted on the bottom of the cases.... and then we started running a hyd motor with a return directly into the diff housing.... which most likely stirred everything up and rinsed it into the screen.

After the first planting season the belly pump shelled out when dad was applying anhydrous. He took it in to Scharber's for the repair. It worked fine for a while, but then the front pump quit... back to the dealer where that got replaced. It still didn't seem right, but we used it anyway. 

I have been thinking it had something to do with the priority valve and the steering since turning the wheel would make it turn over easier. I also have read a few things about low pressure losses starving the high pressure pump.... such as the PTO control valve, and there was mention of a check valve in the forward flowing supply line. I have suspected that pickup tube and hope thats not it. I admit I didn't even know about the pick up screen, I've never been inside a 10 or 20 series Deere behind the clutch housing beyond youtube videos. 

Hopefully it's as simple as cleaning the screen, I won't tell ol dad what I did to fix it and can keep my #1 son status ;) I appreciate everyone's input and will keep you posted, thanks.

SW

If your pickup screen is plugged you need to put brakes in it. The only time screen plugs is with fiber like brake material. And if you don't brakes will continue grinding sending particles to your pump. There is a small screen in the pump that will be plugged if you have any brake material in your trans screen. Good luck with it, you generally never see any issues after the pump on those older tractors. Once again though for everyone reading this if you have pipes replaced with hydraulic hoses on a 10 through 55 series JD put the right pipe on.

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